Tea has a strong ability to absorb moisture and odors, making it easy for the leaves to absorb moisture and off-flavors from the air. If stored improperly, tea can lose its flavor in a short period of time, and the more delicate and fragrant the tea, the harder it is to preserve. Over time, the aroma, color, taste, and appearance of tea will change, with the fresh flavor of new tea disappearing and an aged flavor emerging.

Especially during summer, the hot and humid weather makes it easier for microorganisms to grow, so extra care must be taken when storing tea.

One

Why Does Tea Deteriorate?

The main reasons for tea deterioration are as follows:

1

Oxygen

When the oxygen content within the tea packaging container is controlled below 0.1%, the tea maintains its flavor and aroma well; however, when the oxygen content exceeds 5%, the tea gradually deteriorates.

2

Light

Light accelerates the degradation of pigments and oxidation of lipids in tea, hastening the tea's deterioration and aging. Tea pigments are highly sensitive to light, especially chlorophyll b, which is yellow-green and easily degrades under light exposure, causing the dry tea to become dull in color.

3

Increase in Moisture Content

When the moisture content of tea is between 3% and 5%, it effectively prevents oxidation and deterioration; however, if the moisture content is greater than 12%, mold growth occurs, producing an aged flavor that significantly affects the quality of the tea.

Two

What Key Points Should Be Observed When Storing Tea?

1

Prevent Moisture

Different types and processing methods of tea have varying requirements for moisture content when stored. The most suitable moisture content for storage should be chosen based on the specific type of tea. Most teas benefit from being stored at a low moisture content and in a dry environment to extend their shelf life better.

Although summer is not as humid as spring, there is still plenty of rain, and tea can easily absorb moisture from the air. Therefore, it is essential to seal the packaging properly and not expose the tea to the air.

2

Avoid High Temperatures

Low or constant temperatures can slow down the deterioration of tea. However, when storing tea at low temperatures, one must consider the impact of differences in tea types and external environments on the quality of the stored tea. For example:

Green Tea: The lower the storage temperature, the more quality components are retained in green tea, resulting in better sensory quality. Therefore, many studies suggest refrigeration as the best method for storing green tea.

Black tea: Studies show that low temperatures (0-10°C) effectively slow down the deterioration of black tea; constant temperatures (26°C) also have a certain slowing effect; however, room temperatures (12-25°C) have the greatest impact on the quality of black tea.

Oolong Tea: Oolong tea does not necessarily require very low temperatures for storage; refrigeration at 5°C is more effective than freezing at -18°C or room temperature.

White tea: The optimal storage temperature for white tea is 10-33°C. Temperatures that are too high or too low are not conducive to its storage. Unlike other teas, white tea is not suitable for refrigerator storage because low temperatures affect the transformation of its biochemical components, hindering the formation of EPSF-like compounds.

3

Prevent Oxidation

To prevent oxidation, tea needs to be isolated from oxygen and sealed tightly. If possible, add an oxygen absorber packet or use a vacuum sealer. Green tea, black tea, and Yellow Tea, which are prone to oxidation, often have nitrogen gas flushed into the packaging to delay deterioration. It's worth noting that dark tea requires some oxygen during storage to accelerate the transformation of its internal components. Therefore, bamboo baskets or kraft paper is generally used for packaging, and the tea is stored in a well-ventilated environment.

4

Avoid Strong Light

Storing tea in the dark effectively slows down the transformation of the substances within the tea, thus delaying its deterioration. This is why tea packaging materials need to have good light-blocking properties.

5

Avoid Off-Flavors

High temperatures make it more noticeable when tea absorbs off-flavors. It is crucial to isolate the tea from any odors and not store it alongside strongly scented items.

Three

How Should Packaging Materials Be Selected?

Generally, tea packaging should be moisture-proof, oxygen-isolating, light-blocking, and sealed, with the lowest possible oxygen and moisture permeability. Compared to ordinary packaging materials, newly developed nanomaterials for green tea packaging have even lower oxygen and moisture permeability, effectively improving the preservation quality of green tea. Double or triple-layer composite materials made by combining high-density polyethylene, polypropylene, polyester, etc., with low-density polyethylene films are ideal for tea preservation packaging. Among three different packaging materials, aluminum-coated composite film (CPP aluminum-coated/PE) had the best preservation effect, followed by aluminum-plastic film (PET/Al/PE), while low-density polyethylene (LDPE) was the least effective. However, tea is not typically packaged using a single material; instead, two or more materials are often combined for packaging to achieve the best preservation results.

In summary, different types of tea have different requirements for storage conditions. Appropriate storage conditions and packaging materials should be selected based on the tea's inherent qualities and market demands to stabilize or improve the tea's quality and prolong its storage period.

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